The present invention relates to an excavator, in particular a self-driving, hydraulic universal small excavator, for working soil, laying utility pipes, excavating ditches, foundation holes, etc., with an excavator arm attached to an undercarriage preferably by means of a turning mechanism, with control and driving devices, as well as with at least one pair of wheels fixed to either side of an axle.
Excavators of this kind are generally known and are used for the most varied tasks in numerous different environmental conditions. Even relatively small excavators, so-called universal small excavators, are expected to master important tearing and breaking forces, which causes no problems as far as the engine in concerned. However, particularly under certain ground conditions as for example hard surfaces such as concrete, asphalt, etc., it can prove difficult to secure the said excavators sufficiently so that the available forces can be fully used. Additional stabilizing devices such as retractable supports are only partly successful. On the other hand, the excavators are expected to be fully suitable for cross country operation, i. e. they should be able to work on less solid ground without sinking too deeply, i. e. the seating pressure of the excavator should be as little as possible It is self-evident that also the center of gravity of the excavator should be as far down as possible and that the same should above all hold true for the turning point of the excavator arm. On the other hand, maneuverability, speed and compactness with little need of space are also strongly asked for. The excavators known so far could only partly fulfill these requirements. One reason for that is that tall wheels are needed to adapt the excavator sufficiently for cross country conditions, i. e to enable it to go uneven ground with depressions and holes without touching down. On the other hand, while coping with the above demands, the center of gravity of the excavator and in particular the turning point of the excavator arm are automatically raised if a 360-degree-turn of a superstructure accommodating the excavator arm is asked for. In the other case, increasing the size of the wheels is paramount to reducing the maneuverability of the superstructure.